Multi-beam satellite-borne AIS signal receiving system and method based on time modulation metasurface

A technology of time modulation and signal reception, applied in multi-frequency code systems, signal channels, etc., can solve the problems of increasing spaceborne load resource overhead, performance degradation, and the probability of time slot conflicts affecting satellite ground coverage capabilities

Active Publication Date: 2021-04-20
SHANGHAI SATELLITE ENG INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Narrowing the antenna beam reduces the probability of time slot conflicts and affects the satellite's ground coverage capability. The requirement of narrow beams for the antenna caliber significantly increases the resource overhead of the spaceborne load. The signal domain processing method improves the performance in areas with high ship density. serious decline

Method used

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  • Multi-beam satellite-borne AIS signal receiving system and method based on time modulation metasurface
  • Multi-beam satellite-borne AIS signal receiving system and method based on time modulation metasurface
  • Multi-beam satellite-borne AIS signal receiving system and method based on time modulation metasurface

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Embodiment 1

[0060] According to the design method of the multi-beam space-borne AIS signal receiving system based on the time modulation metasurface provided by the present invention, the system includes a time modulation digital coding metasurface antenna system, a radio frequency subsystem, and a baseband signal processing subsystem.

[0061] Please refer to figure 1 , the time-modulated metasurface array is composed of 64 one-bit reflective digital metasurface units. The digital encoding unit is characterized by integrating a PIN diode in its structure. By applying different bias voltages to the PIN diode, the supersurface The surface units present two different phase responses of 0 degrees and 180 degrees, corresponding to the digital "0" and the digital "1" respectively. By optimizing the control of the unit code distribution and the periodic timing of the code on the digital metasurface, the beam pattern can be realized. Integration, beam scanning, and simultaneous multi-beam covera...

Embodiment 2

[0079] One-bit digitally coded metasurface unit

[0080] Please also see Figure 2 to Figure 5 .

[0081] figure 2 and image 3 The structural diagram and dimensioning diagram of a one-bit metamaterial unit are given respectively. It can be seen that a one-bit digital coded metasurface unit integrated with a PIN diode is used. The unit structure includes: reflective metal patch, PIN diode, metal floor , Ground vias, symmetrical center bias control lines, terminal open fan-shaped stubs, etc. Among them, in order to effectively reduce the interference of the bias control line to high-frequency signals, the center bias control line adopts a symmetrical design and is located in the central weak field strength area of ​​the reflective metal patch; at the same time, the front end of the center bias control line An open-terminated fan stub is further integrated to further improve the isolation between the RF signal and the bias DC. Two different bias voltages are applied to the...

Embodiment 3

[0084] Time-modulated metasurfaces enable simultaneous multiple beams

[0085] Please also see Figure 6 to Figure 10 .

[0086] Assume that the element spacing of the 8x8 time-modulated metasurface is half a wavelength (93.75cm), and the distance between the feed source and the center point of the metasurface is 2.5 wavelengths. The goal of the design is to form 4 beams at the same time, pointing at (15°, 0°), (15°, 180°), (45°, 0°) and (45°, 180°) respectively. That is, the beam pointing of the positive first harmonic component is (15°, 0°), the beam pointing of the negative first harmonic component is (15°, 180°), the beam pointing of the positive third harmonic component is (45°, 0°), and the negative Beam pointing of the third harmonic component (45°, 180°).

[0087] Since each unit on the time-modulated metasurface has a different distance to the feed source, it can be approximately considered that the amplitude weight on the (m, n)th unit due to the distance is whe...

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Abstract

The invention provides a multi-beam satellite-borne AIS signal receiving system and method based on a time modulation metasurface. The multi-beam satellite-borne AIS signal receiving system comprises the time modulation metasurface and a 1-bit coding unit on the surface; a feed source, a low-noise amplifier, a mixer and a local oscillator connected in sequence, used for carrying out low-noise amplification and down-conversion on a received AIS signal and converting the AIS signal into a digital domain; and a low-pass filter and an analog-to-digital converter, sequentially connected, and the mixer. The low-pass filter and the analog-to-digital converter are used for controlling and periodically modulating the phase of the one-bit coding unit on the time modulation metasurface and filtering and demodulating the received AIS signal, so that simultaneous multi-beam detection of the AIS signal is realized. According to the system, the implementation difficulty of the satellite-borne large-aperture antenna is reduced, and the AIS cells covered by the independent beams are isolated through space / frequency, so that the time slot conflict probability of satellite-borne AIS signal interception is reduced, and the high interception probability is realized.

Description

technical field [0001] The invention relates to the technical field of radio engineering, in particular to a multi-beam satellite-borne AIS signal receiving system and method based on a time-modulated metasurface. Background technique [0002] The Automatic Identification System (AIS system for short) is a ship safety system, which is composed of shore-based (base station) and ship-borne equipment. Such information is broadcast to nearby waters and shore stations through VHF. According to the regulations of the International Telecommunication Union (ITU), AIS signals are sent and received on two VHF channels, CH87B (AIS1, 161.975MHz) and CH88B (AIS2, 162.025MHz). For different ships, the self-organizing time division multiple access protocol continuously broadcasts its own static information and dynamic information through the SOTDMA self-organizing time division multiple access protocol. Because the frequency points of AIS signals are concentrated, and the field of view o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L5/02H04L27/26
Inventor 曹岸杰杨勇陆荣成飞孙伟樊炜
Owner SHANGHAI SATELLITE ENG INST
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